Angiotensin II (5-8) is an endogenous C-terminal fragment of the peptide vasoconstrictor angiotensin II . It inhibits renin release from rat kidney slices at a concentration of 50 μM and relaxes rat aorta pre-contracted with phenylephrine . In vivo, microinjection of angiotensin II (5-8) into the ventrolateral periaqueductal gray (vlPAG) of rats increases mean arterial pressure (MAP) and decreases heart rate (HR) by approximately 2.7- and 3-fold less, respectively, than angiotensin II. It increases the latency to withdrawal in a tail-flick test and the mechanical withdrawal threshold in an incision allodynia test in rats when administered at a dose of 0.2 nmol into the vlPAG. Angiotensin II (5-8) (0.4 nmol, vlPAG microinjection) reduces the number of entries and time spent in the open arms of the elevated plus maze and increases the mean startle amplitude, a measure of conditioned fear, in response to foot shock.